 /*******************************************************************************
  * Copyright (c) 2005, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/

 package org.eclipse.ui.internal;

 import org.eclipse.core.runtime.Assert;
 import org.eclipse.jface.action.Action;
 import org.eclipse.ui.IPerspectiveDescriptor;
 import org.eclipse.ui.IWorkbenchPage;
 import org.eclipse.ui.IWorkbenchWindow;
 import org.eclipse.ui.actions.ActionFactory;

 /**
  * Abstract superclass of actions which are enabled iff there is an active perspective
  * in the window.
  *
  * @since 3.1
  */
 public abstract class PerspectiveAction extends Action implements ActionFactory.IWorkbenchAction {
     
     /**
      * The workbench window containing this action.
      */
     private IWorkbenchWindow workbenchWindow;
     
     /**
      * Tracks perspective activation, to update this action's
      * enabled state.
      */
     private PerspectiveTracker tracker;

     /**
      * Constructs a new perspective action for the given window.
      *
      * @param window the window
      */
     protected PerspectiveAction(IWorkbenchWindow window) {
         Assert.isNotNull(window);
         this.workbenchWindow = window;
         tracker = new PerspectiveTracker(window, this);
     }
     
     /**
      * Returns the window, or <code>null</code> if the action has been disposed.
      *
      * @return the window or <code>null</code>
      */
     protected IWorkbenchWindow getWindow() {
         return workbenchWindow;
     }
     
     /* (non-Javadoc)
      * Method declared on IAction.
      */
     public void run() {
         if (workbenchWindow == null) {
             // action has been disposed
 return;
         }
         IWorkbenchPage page = workbenchWindow.getActivePage();
         if (page != null && page.getPerspective() != null) {
             run(page, page.getPerspective());
         }
     }
     
     /**
      * Runs the action, passing the active page and perspective.
      *
      * @param page the active page
      * @param persp the active perspective
      */
     protected abstract void run(IWorkbenchPage page, IPerspectiveDescriptor persp);

     /* (non-Javadoc)
      * Method declared on ActionFactory.IWorkbenchAction.
      */
     public void dispose() {
         if (workbenchWindow == null) {
             // already disposed
 return;
         }
         tracker.dispose();
         workbenchWindow = null;
     }

 }


